Reactive hot melt adhesive

ABSTRACT

The present disclosure relates to silane reactive hot melt adhesive compositions including acid functional wax and basic functional wax; the production of such adhesives; and the use of such adhesives. The silane reactive hot melt adhesive compositions have improved green strength as compared to silane reactive hot melt adhesive compositions without the acid functional wax and basic functional wax.

FIELD

This invention relates to silane reactive hot melt adhesive compositionshaving improved green strength, the production of such adhesives and theuse of such adhesives.

BACKGROUND

Hot melt adhesive compositions are solid at room temperature but, uponapplication of heat, melt to a liquid or fluid state in which moltenform they are applied to a substrate. On cooling, the adhesivecomposition regains its solid form. The hard phase(s) formed uponcooling of the adhesive composition impart all of the cohesion(strength, toughness, creep and heat resistance) to the final bond. Hotmelt adhesive compositions are thermoplastic and can be heated to afluid state and cooled to a solid state repeatedly. Hot melt adhesivecompositions do not include water or solvents.

Curable or reactive hot melt adhesive compositions are also solid atroom temperature and, upon application of heat, melt to a liquid orfluid state in which molten form they are applied to a substrate. Oncooling, the adhesive composition regains its solid form. The phase(s)formed upon cooling of the adhesive composition and prior to curingimpart initial or green strength to the bond. The adhesive compositionwill cure by a chemical crosslinking reaction upon exposure to suitableconditions such as exposure to moisture. Before curing the adhesivecomposition remains thermoplastic and can be remelted and resolidified.Once cured, the adhesive composition is in an irreversible solid formand is no longer thermoplastic. The crosslinked adhesive compositionprovides strength, toughness, creep and heat resistance to the finalbond. Hot melt curable adhesive compositions can provide higher strengthand heat resistance compared to non-curable hot melt adhesivecompositions.

The ability of a reactive hot melt adhesive composition to cool so thatthe solidified but non-crosslinked composition can quickly bond partstogether is called green strength. An adhesive composition that quicklydevelops green strength is desirable in commercial operations as itallows bonded parts to be further processed quickly. Reactive hot meltadhesive compositions will cure under appropriate conditions such asexposure to moisture so that strength of the adhesive bond between partswill continue to rise. A high cured strength is desirable in commercialoperations as it allows stressed parts to be bonded.

In some applications such as roller coating the adhesive composition ismelted in the reservoir of roller coating equipment and applied as athin film by a roller to a substrate. The molten adhesive composition inthe roller coating equipment will react with moisture in the air andbegin to crosslink. At some time the cross linking will progress to apoint where the equipment must be shut down so the partially crosslinked adhesive composition can be removed and the equipment cleaned.Failure to clean the partially crosslinked adhesive composition can leadto application difficulties and ultimately to the composition fullycuring and solidifying in the equipment, requiring equipment shutdownand extensive disassembly. Thus, a long working life is desirable.

Some adhesive compositions will form a string between the just coatedsubstrate and application equipment such as a roller coater when thecoated substrate is removed from the equipment. These hot adhesivestrings are undesirable as they accumulate on the equipment and requirecleaning. Thus, minimizing stringing is desirable. These requirementsare conflicting. An adhesive composition that crosslinks quickly toprovide cured strength will have a short working life. An adhesivecomposition that crosslinks slowly will have a long working life butwill develop strength more slowly, slowing subsequent commercialoperations. It can be difficult to find one reactive hot melt adhesivecomposition that has a commercially desirable combination of greenstrength, cured strength, working life and stringing

The majority of reactive hot melts are moisture-curing urethane hot meltcompositions. The reactive components of urethane hot melt compositionsconsist primarily of isocyanate terminated polyurethane prepolymerscontaining urethane groups and reactive isocyanate groups that reactwith surface or atmospheric moisture to chain extend and form a newpolyurethane polymer. Polyurethane prepolymers are conventionallyobtained by reacting diols with diisocyanates. Upon cooling theisocyanate groups in the polyurethane prepolymer react with moisturefrom the environment to form a crosslinked irreversible solid bond.

Moisture-curing urethane hot melt adhesive compositions have certaindisadvantages. One disadvantage is the residual monomer content ofpolyisocyanates, more particularly the more volatile diisocyanates. Somemoisture-curing urethane hot melt adhesive compositions can containsignificant amounts of unreacted monomeric diisocyanates. At the hotmelt application temperature (typically at 100° C. to 170° C.) monomericdiisocyanates have a considerable vapor pressure and may be partlyexpelled in gaseous form. The isocyanate vapors may be toxic, irritatingand have a sensitizing effect, so that precautionary measures have to betaken in the application process.

Silane reactive hot melt adhesive compositions have been developed toavoid disadvantages of isocyanate reactive hot melt compositions. Silanereactive hot melt adhesive compositions are also solid at roomtemperature and, upon application of heat, melt to a liquid or fluidstate in which molten form they are applied to a substrate. On cooling,the composition regains its solid form. Silane reactive hot meltadhesive compositions are based on silane modified polymers thatcomprise moisture reactive silane groups that form siloxane bonds whenexposed to moisture such as in the atmosphere. Silane reactive hot meltadhesive compositions can be free of residual isocyanate monomers andisocyanate functionality. Silane reactive hot melt adhesive compositionsoffer good cured adhesion and since there is no isocyanate there are noconcerns about emission of isocyanate monomer vapor. However, silanereactive hot melt adhesive compositions develop green strength slowerthan reactive polyurethane hot melt adhesive compositions.

There remains a need for a silane reactive hot melt adhesive compositionthat has a desirable combination of properties for commercial useincluding quick development of green strength, a long working life andhigh final (cured) strength.

BRIEF SUMMARY

It has been discovered that a silane reactive hot melt adhesivecomposition comprising a silane modified polymer; an effective amount ofbasic functional wax; and optionally, an effective amount of acidicfunctional wax develops green strength more quickly and has an extendedworking life and higher final strength after cure as compared to thesame silane modified hot melt adhesive composition with no functionalwax or the same silane modified hot melt adhesive composition with onlyacidic functional wax. One embodiment is directed to a silane reactivehot melt adhesive composition comprising a silane modified polymer, aneffective amount of acidic functional wax, an effective amount of basicfunctional wax and a silane adhesion promoter. Preferably, the silaneadhesion promoter is an aminosilane adhesion promoter.

Another embodiment is directed to a method of increasing the developmentof green strength in a silane reactive hot melt adhesive composition byadding an effective amount of acidic functional wax and an effectiveamount of basic functional wax.

Another embodiment is directed to a method for bonding materialstogether which comprises applying the silane reactive hot melt adhesivecomposition in a molten form to a first substrate, bringing a secondsubstrate in contact with the molten composition applied to the firstsubstrate, and subjecting the applied composition to conditions whichwill allow the composition to cool and cure to an irreversible solidform, said conditions comprising moisture.

Another embodiment is directed to an article of manufacture comprising asubstrate bonded to cured reaction products of a silane reactive hotmelt adhesive composition prepared from a silane modified polymer andcontrolled ranges of both acidic functional wax and basic functionalwax.

The disclosed compounds include any and all isomers and stereoisomers.In general, unless otherwise explicitly stated the disclosed materialsand processes may be alternately formulated to comprise, consist of, orconsist essentially of, any appropriate components, moieties or stepsherein disclosed. The disclosed materials and processes mayadditionally, or alternatively, be formulated so as to be devoid, orsubstantially free, of any components, materials, ingredients,adjuvants, moieties, species and steps used in the prior artcompositions or that are otherwise not necessary to the achievement ofthe function and/or objective of the present disclosure.

When the word “about” is used herein it is meant that the amount orcondition it modifies can vary some beyond the stated amount so long asthe function and/or objective of the disclosure are realized. Theskilled artisan understands that there is seldom time to fully explorethe extent of any area and expects that the disclosed result mightextend, at least somewhat, beyond one or more of the disclosed limits.Later, having the benefit of this disclosure and understanding theconcept and embodiments disclosed herein, a person of ordinary skillcan, without inventive effort, explore beyond the disclosed limits and,when embodiments are found to be without any unexpected characteristics,those embodiments are within the meaning of the term about as usedherein.

DETAILED DESCRIPTION

The disclosures of all documents cited herein are incorporated in theirentireties by reference.

As used herein, “irreversible solid form” means a solid form wherein thesilane reactive hot melt adhesive composition has crosslinked to producea cured, thermoset, insoluble material.

The silane reactive hot melt adhesive composition comprises one or moresilane modified polymers. The silane modified polymer has an organicbackbone, bearing one or more terminal or pendant silane or alkoxylatedsilane groups. The silane groups are hydrolyzed by water to silanolgroups, which can condense with each other or with reactive species onthe adherent surfaces. The silane modified polymer may be prepared withone or more of a variety of polymer backbones such as polyurethane (forexample derived from Baycoll 2458 from Bayer), polyether, polyester,polyetherester, polyesterether, polyolefin, polycaprolactone,polyacrylate, polybutadiene, polycarbonate, polyacetal, polyester amide,polythioether, polyolefin and the like. Advantageous backbones for thesilane modified polymer include polyurethane and polyether andespecially acrylate modified polyether (prepared for instance asdescribed in U.S. Pat. No. 6,350,345, the contents of which areincorporated reference). The silane modified polymer organic backbonecan be free of silicon atoms. The silane modified polymer can be a lowmodulus silane modified polymer having a Young's modulus for the cured,neat polymer lower than 50 psi; a high modulus silane modified polymerhaving a Young's modulus for the cured, neat polymer equal or greaterthan 50 psi; or a combination of low modulus silane modified polymer andhigh modulus silane modified polymer.

The silane modified polymer can be represented by the formulaR-[A-Si(C_(x)H_(2x+1))_(n)(OC_(y)H_(2y+1))_(3-n)]_(z)wherein R is the organic backbone;

A is a linkage that links the silane to polymer backbone R;

n=0, 1 or 2;

x and y are, independently a number from 1 to 12.

The number of silane groups z will preferably be more than one permolecule (to generate a fully cured network), and more preferably atleast two per molecule. More preferably, the silane functional polymeris telechelic or end-functionalized, where most or all the ends aresilane functional. The number of silyl ether groups per silane endgroup, 3-n, is preferably 2 or 3 (n=1 or 0). The silane reactive hotmelt adhesive composition cures during exposure to water or moisture,when the silane groups are hydrolyzed to silanol groups which cancondense with each other or with reactive species on the surfaces to bebonded.

Silane modified polymers are commercially available, for example, fromMomentive Performance Material under the trade name SPUR, from HenkelCorporation under the trade name FLEXTEC and from Kaneka Corporationunder the trade name MS polymer and SILYL polymer.

The silane modified polymer is advantageously liquid at roomtemperature.

The amount of silane modified polymer in the composition will depend onits molecular weight and functionality, but will typically be from 20-80wt %, advantageously 25-60 wt %, and more advantageously from 30-50 wt%, based on the total weight of the adhesive composition.

The silane reactive hot melt adhesive composition can optionallycomprise a controlled amount of acidic functional wax. By “acidicfunctional wax” it is meant that the wax includes a functional moietythat is acidic. The acidic functional wax can have terminal or pendantacidic functional moieties.

Ullmann's Encyclopedia of Industrial Chemistry, the contents of whichare incorporated by reference herein, describes waxes. Examples of typesof waxes that may be used include natural waxes, partially syntheticwaxes and fully synthetic waxes. Natural waxes are formed throughbiochemical processes and are products of animal or plant metabolism.Partially synthetic waxes are formed by chemically reacting naturalwaxes. Fully synthetic waxes are prepared by polymerizing low molar massstarting materials such as carbon, methane, ethane or propane. The twomain groups of fully synthetic waxes are the Fischer-Tropsch waxes andpolyolefin waxes such as polyethylene wax, polypropylene wax andcopolymers thereof.

Acidic functional groups are added to the wax molecule by, for example,grafting synthetic waxes with an acidic moiety such as carboxylic acidor maleic anhydride or by cleavage of the esters and/or oxidation of thealcohols in partially synthetic waxes. Acidic functional waxes can havea saponification number (mg KOH/gm wax) of less than about 90 and moreadvantageously from about 5 to about 30. Some useful acid functionalmaleated waxes can have about 50% to about 95% of maleic anhydridemoieties bound to the wax backbone with the remaining maleic anhydridecontent not bound to the wax backbone.

Acidic functional waxes are available commercially, for example fromClariant International Ltd, Switzerland; EPChem International Pte Ltd,Singapore; Honeywell International Inc., U.S. and Westlake ChemicalCorp, U.S. Advantageous acid functional waxes are the maleatedpolypropylene waxes. One useful maleated polypropylene wax is A-C 1325Pavailable from Honeywell International Inc.

The use of acid functional wax in the silane reactive hot melt adhesivecomposition is optional. Advantageously, the silane reactive hot meltadhesive composition will contain an effective amount of acid functionalwax. An effective amount of acid functional wax is the amount of acidfunctional wax that will increase green strength of a silyl reactive hotmelt adhesive composition without deleteriously degrading otherproperties of that composition. Surprisingly, while some amount of waxis required to more quickly provide green strength to the silanereactive hot melt adhesive composition the use of too much wax candeleteriously degrade properties of the composition such as curedstrength. Thus, the amount of acid functional wax in the silane reactivehot melt adhesive composition must be kept in a controlled range. Thesilane reactive hot melt adhesive composition will contain 0.1 wt % toabout 15 wt % of acid functional wax based on the total weight of theadhesive composition. Advantageously, the silane reactive hot meltadhesive composition will contain 0.1 wt % to about 8 wt % or even 0.1wt % to about 4 wt % of acid functional wax based on the total weight ofthe adhesive composition.

The silane reactive hot melt adhesive composition comprises an effectiveamount of basic functional wax. By “basic functional wax” it is meantthat the wax includes at least one functional moiety that is basic, forexample amide moieties or amine moieties. The basic functional wax canhave terminal, within the backbone, or pendant basic functionalmoieties. Basic functional groups are added to the wax molecule by, forexample, grafting synthetic waxes with a basic moiety such as amine oramide. Basic functional groups can also be introduced by reactingmolecules with basic functionality into the wax molecule.

Basic functional waxes are available commercially, for example fromHoneywell International Inc., U.S. and Vertellus Inc., Greensboro, N.C.and Crayvallac Inc. Advantageous basic functional waxes are the amineand amide functional waxes. Useful basic functional waxes includeACumist from Honeywell International Inc. and Paricin 220 from VertellusPerformance Materials Inc, etc.

The silane reactive hot melt adhesive composition will contain aneffective amount of basic functional wax. Surprisingly, addition ofbasic functional wax to reactive hot melt adhesive composition comprisedof a silane modified polymer and acid functional wax allows theresulting composition to more quickly provide green strength as comparedto the reactive hot melt adhesive composition without the basic wax.

An effective amount of basic functional wax is the amount of basicfunctional wax that will increase green strength of a reactive hot meltadhesive composition comprised of a silane modified polymer and acidfunctional wax without deleteriously degrading other properties of thatcomposition. Surprisingly, while some amount of basic functional wax isrequired to improve green strength of the silane reactive hot meltadhesive composition the use of too much basic functional wax appears todeleteriously degrade properties of the composition such as curedstrength. Thus, the amount of basic functional wax in the silanereactive hot melt adhesive composition must be kept in a controlledrange. The silane reactive hot melt adhesive composition will containabout 0.05 wt % to about 8 wt % of basic functional wax based on thetotal weight of the adhesive composition. Advantageously, the silanereactive hot melt adhesive composition will contain about 0.2 wt % toabout 4 wt % of basic functional wax based on the total weight of theadhesive composition. More advantageously, the silane reactive hot meltadhesive composition will contain about 0.2 wt % to about 2 wt % ofbasic functional wax based on the total weight of the adhesivecomposition.

In some embodiments the ratio of acidic functional wax to basicfunctional wax (R_(A:B)) is in the range of 0:1 to 10:1, or simply 0 to10. More preferably, R_(A:B) is in the range of 1.5 to 2.5. While ratiosoutside of this range are useful, this ratio of acidic functional wax tobasic functional wax provides a surprisingly improved effect to greenstrength of the silane reactive hot melt adhesive composition balancedwith good final adhesion strength.

The silane reactive hot melt adhesive composition can optionallycomprise tackifier. The choice of tackifier will depend on the backboneof the silane modified polymer. The tackifier choices include naturaland petroleum-derived materials and combinations thereof as described inC. W. Paul, “Hot Melt Adhesives,” in Adhesion Science and Engineering-2,Surfaces, Chemistry and Applications, M. Chaudhury and A. V. Pociuseds., Elsevier, New York, 2002, p. 718, incorporated by referenceherein.

Useful tackifier for the adhesive composition of the invention includesnatural and modified rosin, aromatic tackifier or mixtures thereof.Useful natural and modified rosins include gum rosin, wood rosin, talloil rosin, distilled rosin, hydrogenated rosin, dimerized rosin,resinates, and polymerized rosin; glycerol and pentaerythritol esters ofnatural and modified rosins, including, for example as the glycerolester of pale, wood rosin, the glycerol ester of hydrogenated rosin, theglycerol ester of polymerized rosin, the pentaerythritol ester ofhydrogenated rosin, and the phenolic-modified pentaerythritol ester ofrosin. Examples of commercially available rosins and rosin derivativesthat could be used to practice the invention include Sylvalite RE 110L,Sylvares RE 115, and Sylvares RE 104 available from Arizona Chemical;Dertocal 140 from DRT; Limed Rosin No. 1, GB-120, and Pencel C fromArakawa Chemical. One useful natural and modified rosin is a rosin estertackifier such as KE-100, available from Arakawa Chemical Co. Anotheruseful rosin ester tackifier is a Komotac 2110 from Komo Resins. Usefularomatic tackifiers include styrenic monomers, styrene, alpha-methylstyrene, vinyl toluene, methoxy styrene, tertiary butyl styrene,chiorostyrene, coumarone, indene monomers including indene, and methylindene. Preferred are aromatic hydrocarbon resins that arephenolic-modified aromatic resins, C₉ hydrocarbon resins,aliphatic-modified aromatic C₉ hydrocarbon resins, C₉ aromatic/aliphaticolefin-derived and available from Sartomer and Cray Valley under thetrade name Norsolene and from Rutgers series of TK aromatic hydrocarbonresins. Other useful aromatic tackifiers are alpha-methyl styrene typessuch as Kristalex 3100, Kristalex 5140 or Hercolite 240, all availablefrom Eastman Chemical Co.

The tackifier component will usually be present in an amount of fromabout 15 wt % to about 90 wt %, advantageously from about 20 wt % toabout 50 wt %, more advantageously from about 25 wt % to about 40 wt %,based on the total weight of the adhesive composition. The rosintackifier will be present from 0 to 30 wt %, advantageously from about 5to about 25 wt %, based on the total weight of the adhesive composition.The aromatic tackifier will be present from 0 to about 60 wt %,advantageously from about 15 to about 40 wt %, based on the total weightof the adhesive composition.

The silane reactive hot melt adhesive composition can optionallycomprise an acrylic polymer or copolymer (acrylic polymer). The acrylicpolymer can improve green strength of the cooled hot melt adhesivecomposition. The acrylic polymer can be either a silane-reactive polymeror non-reactive polymer. A silane reactive polymer comprises groups suchas carboxylic acid, amine, thiol and hydroxyl that react with silanemoieties. A preferred silane reactive group is carboxylic acid. Thenumber of groups should be sufficient such that a significant amount, atleast 5%, of the acrylic polymer is grafted to the silane modifiedpolymer via the silane groups. A non-silane reactive acrylic polymerdoes not include groups that are reactive with the silane modifiedpolymer.

One useful reactive acrylic polymer is Elvacite 2903 from INEOSAcrylics. Elvacite 2903 is a solid acrylic copolymer comprising acid andhydroxyl groups, has an acid number 5.2 and hydroxyl number of 9.5.

The amount of solid acrylic polymer in the adhesive composition willdepend on a number of factors, including the glass transitiontemperature and molecular weight of the acrylic polymer, but willtypically be present in an amount of from about 10 to about 45 wt %,based on the total weight of the adhesive composition.

The silane reactive hot melt adhesive composition can optionallycomprise a catalyst. Suitable curing agents for the silane groups aredescribed in U.S. Patent Publication No. 2002/0084030, and incorporatedby reference herein. Exemplary catalysts includes bismuth compounds suchas bismuth carboxylate; organic tin catalysts such as dimethyltindineodecanoate, dibutyltin oxide and dibutyltin diacetate; titaniumalkoxides (TYZOR® types, available from DuPont); tertiary amines such asbis(2-morpholinoethyl) ether, 2,2′-Dimorpholino Diethyl Ether (DMDEE)and triethylene diamine; zirconium complexes (KAT XC6212, K-KAT XC-A209available from King Industries, Inc.); aluminum chelates (K-KAT 5218,K-KAT 4205 available from King Industries, Inc.), KR types (availablefrom Kenrich Petrochemical, Inc.); and other organometallic compoundsbased on Bi, Sn, Zn, Co, Ni, and Fe and the like. The level of catalystin the silane reactive hot melt adhesive composition will depend on thetype of catalyst used, but can range from about 0.05 to about 5 wt %,advantageously from about 0.1 to about 3 wt % and more advantageouslyfrom about 0.1 to about 2 wt %, based on the total weight of theadhesive composition.

The silane reactive hot melt adhesive composition can optionallycomprise a moisture scavenger to extend pot life, such as vinyltrimethoxy silane or methacryloxypropyltrimethoxysilane. The level ofmoisture scavenger employed can be from 0 to 3% and preferably from 0 to2%, based on the total weight of the adhesive composition.

The adhesive composition can comprise an adhesion promoter or couplingagent which promotes bonding of the composition to a substrate. Examplesare described in: Michel J. Owen, “Coupling agents: chemical bonding atinterfaces”, in Adhesion Science and Engineering-2, Surfaces, Chemistryand Applications, M. Chaudhury and A. V. Pocius eds., Elsevier, NewYork, 2002, p. 403, incorporated by reference herein. Preferred adhesionpromoters include organo-silanes which can link the silane-functionalpolymer to the surface such as amino silanes and epoxy silanes. Someexemplary aminosilane adhesion promoters include3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane,N-(2-aminoethyl-3-aminopropyl)trimethoxysilane,3-aminopropylmethyldiethoxysilane,4-amino-3,3-dimethylbutyltrimethoxysilane,N-(n-butyl)-3-aminopropyltrimethoxysilane,1-butanamino-4-(dimethoxymethylsilyl)-2,2-dimethyl,(N-cyclohexylaminomethyl)triethoxysilane,(N-cyclohexylaminomethyl)-methyldiethoxysilane,(N-phenylaminoethyl)trimethoxysilane,(N-phenylaminomethyl)-methyldimethoxysilane orgamma-ureidopropyltrialkoxysilane. Particularly preferred amino silanesinclude 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane.Some exemplary epoxy silane adhesion promoters include3-glycidyloxypropyltrimethoxysilane, 3-glycidyloxypropyltriethoxysilaneor beta-(3,4-epoxycyclohexyl)ethyltrimethoxysilane. Other silaneadhesion promoters include mercaptosilanes. Some exemplarymercaptosilane adhesion promoters include3-mercaptopropyltrimethoxysilane, 3-mercaptopropylmethyldimethoxysilaneor 3-mercaptopropyltriethoxysilane. The level of adhesion promoteremployed can be from 0 to 10 wt %, preferably 0.1 wt % to 5 wt % andmore preferably 0.2 wt % to 3 wt % based on the total weight of theadhesive composition. The adhesion promoter may act as a crosslinker or,if more reactive to moisture than the silane modified polymer, can alsoserve as a moisture scavenger.

The silane reactive hot melt adhesive composition can optionallycomprise conventional additives known to a person skilled in theadhesive art. Conventional additives which are compatible with thedisclosed adhesive composition may simply be determined by combining apotential additive with the composition and determining if they remainhomogenous. Non-limiting examples of suitable additives include, withoutlimitation, fillers, plasticizers, defoamers, rheology modifiers, airrelease agents and flame retardants.

The total level of additives will vary depending on amount of eachparticular additive needed to provide the silane reactive hot meltadhesive composition with desired properties. The level of additives canbe from 0 to 50 wt % based on the total weight of the adhesivecomposition.

An exemplary silane reactive hot melt adhesive composition is shownbelow.

range preferred range component (wt %) (wt %) silane modified polymer20-80 30-60 acidic functional wax 0.1-15  0.5-8  basic functional wax0.1-8  0.2-4  ratio acid functional wax:basic ≧0  0-10 functional wax(R_(A:B)) natural and modified rosin tackifier  0-30  3-20 aromatictackifier  0-60 10-35 acrylic polymer 10-45 15-35 catalyst 0.05-5  0.05-2   moisture scavenger 0-3  0-1.5 adhesion promoter  0-10 0.1-2 additives  0-50  5-40 R 0.1-1.8 0.3-1.2

The silane reactive hot melt adhesive composition is preferably free ofwater and/or solvent in either the solid and/or molten form.

The silane reactive hot melt adhesive composition can be prepared bymixing the tackifier, waxes and other non-reactive components with heatuntil homogeneously blended. The mixer is placed under vacuum to removemoisture followed by heated mixing of the reactive components.

The silane reactive hot melt adhesive compositions can be used to bondarticles together by applying the hot melt adhesive composition inheated, molten form to a first article, bringing a second article incontact with the molten composition applied to the first article. Afterapplication of the second article the silane reactive hot melt adhesivecomposition is subjected to conditions that will allow it to solidify,bonding the first and second articles. Solidification occurs when theliquid melt is subjected to a temperature below the melting point,typically room temperature. The phase(s) formed upon cooling of theadhesive composition and prior to curing impart initial or greenstrength to the bond. After solidification the adhesive is exposed toconditions such as surface or atmospheric moisture that crosslink andcure the solidified composition to an irreversible solid form.

The silane reactive hot melt adhesive compositions are useful forbonding articles composed of a wide variety of substrates (materials),including but not limited to wood, metal, polymeric plastics, glass andtextiles. Non-limiting uses include use in the manufacture of footwear(shoes), use in manufacture of windows and doors including entry doors,garage doors and the like, use in the manufacture of panels, use inbonding components on the exterior of vehicles, and the like.

Application temperatures of the silane reactive hot melt adhesivecompositions are determined by the thermal stability of the compositionand the heat sensitivity of the substrates. Preferred applicationtemperatures are above 120° C. and below 170° C., more preferably below150° C., and most preferably below 140° C.

The silane reactive hot melt adhesive compositions may be then appliedin molten form to substrates using a variety of application techniquesknown in the art. Examples includes hot melt glue gun, hot melt slot-diecoating, hot melt wheel coating, hot melt roller coating, melt blowncoating, spiral spray and the like. In preferred embodiments the hotmelt adhesive composition is applied to a substrate using hot meltroller coater or extruded onto a substrate.

The invention is further illustrated by the following non-limitingexamples.

EXAMPLES

The following tests were used in the Examples.

Acid number (ASTM D-1386)—Standard Test Method for Acid Number(Empirical) of Synthetic and Natural Waxes

Saponification number (ASTM D-1387)—Standard Test Method forSaponification Number (Empirical) of Synthetic and Natural Waxes

Viscosity—viscosity was measured using a Brookfield digital viscometerwith a Thermosel heating unit, small sample adapter, 27 spindle, (and 13chamber.) Desirably, viscosity of the silane reactive hot melt adhesivecomposition should be about 5,000 to 25,000 cps at 250° F.

Final (cured) strength by Lap Shear Adhesion Test (TLS)—The adhesive wasapplied to a clean PVC substrate. A stainless steel drawdown applicator(BYK-Gardner) was used to obtain a controlled thickness of 0.030 inches.Glass bead spacers 0.020 in thickness were sprinkled on top of theadhesive layer to control the final bondline thickness. Clean glassstrips 1 inch by 3 inches were bonded to the applied adhesive with anoverlapping area of 1 inch by 1 inch using hand pressure. The finishedbonds were conditioned at 72° F./50% RH for two weeks before testing toallow for full moisture cure. Tensile samples were pulled along the longaxis at 0.5 inches/min until failure in an Instron tensile test machineeither at room temperature or immediately after heating the sample for0.5 hr in an oven at 180° F. Desirably, on glass to PVC substrates,final strength of the silane reactive hot melt adhesive compositionshould be greater than 60 psi at room temperature and greater than 20psi at 180° F.

Green Strength and strength development by TLS—Lap shear bonds were madeand tested as described above, but were tested during cure process (2hours, 1 day and one week) after bonding. This test characterizes theability of the bonded structure to survive handling in manufacture priorto full cure. Hot melts have the advantage of high strength in the greenstate which minimizes working inventory.

The following materials were used in the Examples.

A-C 1325P a maleated polypropylene wax available from HoneywellInternational Inc. The manufacturer states that A-C 1325P has 78% boundmaleic anhydride; a saponification number of 18 mg KOH/gm wax; and aviscosity of 1600 cps at 190° C.

Paricine 220 is N-(2-hydroxyethel) 12-hydroxystearamide available fromVertellus Inc., Greensboro, N.C.

MAX 951 is a low modulus silane terminated polyether, commerciallyavailable from Kaneka Corp.

Elvacite 2903 is a solid acrylic polymer, available from Ineos Acrylics.

Kristalex 3100 is an alpha-methyl styrene tackifier, available fromEastman Chemical Co.

A1110 is an adhesion promoter, available from Momentive PerformanceMaterials.

KBM903 is an adhesion promoter, available from Shin Etsu Silicone.

A515 is an air release agent, available from BYK Chemie.

Teckros H95 is a hydrogenated rosin ester tackifier, available fromTeckrez, Inc.

Reaxis C233 is a tin catalyst available from Reaxis Inc.

EB50 866 is a UV absorber available from BASF.

Example 1

Samples of silane reactive hot melt adhesive compositions were preparedaccording to the following table. The air release agent, UV absorber,acrylic polymer, tackifiers and any functional wax were combined, heatedto about 300° F. and stirred until homogeneous. Vacuum was applied toremove any water and the temperature was lowered to about 270° F. Silanemodified polymer was added and vacuum mixed until homogeneous. Theadhesion promoter and catalyst were added and vacuum mixed untilhomogeneous. The final adhesive was poured into a container, sealedunder nitrogen and cooled to room temperature.

Sample A is a comparative example with no acid functionalized wax and nobasic functional wax. Sample B is a comparative example with 8 parts(2.2%) acid functionalized wax and no basic functional wax. Samples 1-4are exemplary inventive examples with 8 parts acid functionalized waxand varying amounts of basic functional wax. Sample 5 is an example with4 parts of basic functional wax and no acid functional wax.

A B 5 1 2 3 4 Material silane modified 140 140 140 140 140 140 140polymer¹ tackifier² 52 52 52 52 52 52 52 acrylic polymer³ 92 92 92 92 9292 92 tackifier⁴ 52 52 52 52 52 52 52 UV absorber⁵ 3 3 3 3 3 3 3 airrelease agent⁶ 3 3 3 3 3 3 3 adhesion promoter⁷ 4 4 4 4 4 4 4 catalyst⁸4 4 4 4 4 4 4 acid functional wax⁹ 0 8 0 8 8 8 8 basic functional 0 0 40.8 1.6 4 8 wax¹⁰ total (grams) 350 358 355 359.8 361.6 365 370(R_(A:B)) — — — 10 5 2 1 ¹Max 951 ²Teckros H95 ³Elvacite 2903 ⁴Kristflex3100 ⁵EB50 866 ⁶A515 ⁷A-1110 ⁸Reaxis C233 ⁹A-C 1325 ¹⁰Paricin 220Property (R_(A:B)) — — — 10 5 2 1 R Clarity Tr¹ Tr Tr Tr Tr Tr TrViscosity (cps 8975 18900 20600 17800 17000 22050 19750 @ 250° F.) ShoreA hardness 63.3 70 65 80 78.7 78.3 80 Strength TLS (psi) glass/PVC 2hours 25 22 40.6 31 32 46 40 failure mode¹ CF AF CF AF AF CF CF 24 hours26 50 56 45 41 68 46 failure mode AF AF CF AF CF CF CF 168 hours 98 10299.6 85 76 101 111 failure mode AF AF CF AF AF AF AF Final Strength TLS(psi) glass/PVC Room temperature 166.8 142.7 102 120.8 130 125.1 99failure mode AF AF AF AF AF AF AF 180° F. 36.2 37 17.1 49.6 36 25.5 23.4failure mode AF AF AF AF AF AF AF ¹Tr indicates sample was translucent 2AF = predominately adhesive failure mode; CF = predominately cohesivefailure mode. The transition from a cohesive failure mode to an adhesivefailure mode indicates crosslinking of the adhesive.

Sample 3 provides the best performance, having the best results in greenstrength and setting speed, as shown by the adhesion results at 2 hours,24 hours and 168 hours. The other samples have lower green strength orweaker final adhesion strength.

Many modifications and variations of this invention can be made withoutdeparting from its spirit and scope, as will be apparent to thoseskilled in the art. The specific embodiments described herein areoffered by way of example only, and the invention is to be limited onlyby the terms of the appended claims, along with the full scope ofequivalents to which such claims are entitled.

The invention claimed is:
 1. A silane reactive hot melt adhesivecomposition comprising: a silane modified polymer; 0.1 wt % to 15 wt %of acidic functional wax based on weight of the adhesive composition;and 0.05 wt % to 8 wt % of basic functional wax based on weight of theadhesive composition.
 2. The silane reactive hot melt adhesivecomposition of claim 1, comprising 0.1 wt % to 2 wt % of basicfunctional wax based on weight of the adhesive composition.
 3. Thesilane reactive hot melt adhesive composition of claim 1 wherein theratio of acidic functional wax to basic functional wax (R_(A B)) is inthe range of 1:80 to 300:1.
 4. The silane reactive hot melt adhesivecomposition of claim 1 further comprising an aminosilane adhesionpromoter.
 5. The silane reactive hot melt adhesive composition of claim1 further comprising an aminosilane adhesion promoter wherein the molarratio of acid functionality from the acidic functional wax and aminofunctionality of the aminosilane (R) is equal to or less than 1.2. 6.The silane reactive hot melt adhesive composition of claim 1 wherein thesilane reactive hot melt adhesive composition is free of isocyanatefunctionality.
 7. The silane reactive hot melt adhesive composition ofclaim 1 further comprising one or more of a tackifier selected from thegroup consisting of rosin ester, hydrogenated hydrocarbon, aromatictackifier or mixtures thereof; an acrylic polymer; and a catalyst. 8.The silane reactive hot melt adhesive composition of claim 1, whereinthe silane modified polymer comprises a plurality of terminal silylgroups each independently having a formula ofA-Si(C_(x)H_(2x+1))_(n)(OC_(y)H_(2y+1))_(3-n), wherein A is a linkage tothe polymer backbone; x is 1 to 12; y is 1 to 12; and n is 0, 1 or 2;and the silyl group of the silane modified polymer isend-functionalized.
 9. The silane reactive hot melt adhesive compositionof claim 1, wherein the silane modified polymer has a backbone structureselected from the group consisting of polyurethane, polyether,polyester, polyacrylate and GP polyolefin.
 10. The silane reactive hotmelt adhesive composition of claim 1, wherein the silane modifiedpolymer has a formulaR-[A-Si(C_(x)H_(2x+1))_(n)(OC_(y)H_(2y+1))_(3-n)]_(z) wherein R is anorganic backbone of the silane modified polymer without silicon atoms, Ais a linkage that links the silane group to the polymer backbone R, n=0,1 or 2; x and y are, independently a number from 1 to 12; and z is atleast one.
 11. The silane reactive hot melt adhesive composition ofclaim 1, wherein the silane modified polymer comprises a plurality oftelechelic silyl groups each independently having a formula ofA-Si(C_(x)H_(2x+1))_(n)(OC_(y)H_(2y+1))_(3-n), wherein A is a linkage tothe polymer backbone; x is 1 to 12; y is 1 to 12; and n is 0, 1 or 2.12. The silane reactive hot melt adhesive composition of claim 1,wherein the silane reactive hot melt adhesive composition is free ofwater and solvent.
 13. A method of applying a silane reactive hot meltadhesive composition comprising: providing the silane reactive hot meltadhesive composition of claim 1 in solid form at room temperature;heating the silane reactive hot melt adhesive composition to a moltenstate at the point of use; applying the molten silane reactive hot meltadhesive composition to a first substrate; bringing a second substratein contact with the molten adhesive composition applied to the firstsubstrate; cooling the applied molten adhesive composition to, a solidstate; subjecting the cooled adhesive composition to conditionssufficient to irreversibly cure the cooled adhesive composition to forma bond between the first and second substrates.
 14. The method of claim13 wherein the step of applying the molten silane reactive hot meltadhesive composition is selected from the group consisting of sprayapplication, extrusion, and roll coating.
 15. An article of manufacturecomprising cured reaction products of the silane reactive hot meltadhesive composition of claim 1.